The SK-5860 is for use with the following panels, which are all addressable:
Silent Knight SK-5700
Silent Knight SK-5808
Silent Knight SK-5820XL
Silent Knight SK-5820XL-EVS
Silent Knight SK-6700
Silent Knight SK-6808
Silent Knight SK-6820
Silent Knight SK-6820EVS
Given you say the system is voice-capable it could be an SK-5820XL-EVS, an SK-6820EVS, or one of the other listed Silent Knight FACPs with a separate voice panel. Don’t know why the system would say “Zone 1” if it’s addressable though (addressable systems have points rather than zones).
Hard to believe the theater staff are completely ignoring everything the system’s telling them: if they had any sense they’d get a technician from their local service company out immediately to check the system over (which is what I’d advise you to tell them to do).